The present disclosure relates to air quality indicators. More particularly, it relates to easy-to-use indicators of elevated airborne fine particle levels.
Air quality is a rising concern in many parts of the world. One air quality parameter of heightened interest is the levels or amount of fine particles of fine particulate matter. Fine particles or fine particulate matter is commonly designated as particles having a diameter of 2.5 μm or less, and is conventionally referred to by the abbreviation “PM2.5”. Airborne fine particles can pose significant health risks, especially at elevated levels in relatively confined areas.
Room air purifiers, HVAC filters and other filter-based systems are widely available for removing particles from air, and are highly useful in improving indoor air quality. The filter media utilized with indoor air filtration systems continues to evolve. More recently, filter media viable for indoor has been developed that readily captures fine particles. Electrostatic treatment of filter media is known to significantly improve the ability of a filter media to capture fine particulate matter. With the inclusion of high electrostatic charge processes and materials, filter media (available, for example, from 3M Company of St. Paul, Minn.) can be produced that has both high fine particle efficiency and low airflow resistance.
Notwithstanding the wide availability, many residential and office space environments do not take advantage of fine particulate air quality solutions. It is surmised that the failure to consider or address elevated fine particle levels arises from the simple fact that the human senses cannot readily perceive the presence of airborne fine particles, even at elevated levels, when indoors (although outdoors, fine particles can create haze). If the presence of airborne fine particles is not brought to the attention of the persons living or working in a certain environment, there may be little motivation to make use of fine particle filtration technology. This can be especially troubling in environments where some attempt at large particle air quality control is in place (e.g., filtration media suited for removing only large particles); under these circumstances, persons living or working in the environment may be under the false impression that the overall air quality is acceptable when in fact a potentially unsafe fine particle level exists. Unfortunately, many regions of the world continue to report excessively high fine particulate levels (PM2.5). As a point of reference, acceptable fine particle levels have been developed by various governmental entities, typically expressed in terms of total particle weight per unit volume of air over time (e.g., micrograms per cubic meter). For example, in 2012 the US EPA reaffirmed a daily PM2.5 air quality standard of 35 μg/m3, and revised downward the annual standard to 12 μg/m3. Recent air quality measurements from major Chinese cities such as Shanghai and Beijing commonly show PM2.5 exceeding 100 μg/m3 in fall, winter, and spring, and occasionally exceeding even 500 μg/m3.
While sensor systems for measuring fine particles levels in air are well known and can produce highly accurate data, they are expensive and relatively complex to operate. Scientists and other research professionals require and rely upon the detailed information these sensor systems can provide, thus justifying the costs. In contrast, persons interested in generally understanding fine particle levels on a gross scale have no need for detailed data and will not invest in available sensor equipment. In fact, the data produced by fine particle level sensors may have little meaning to the average person who likely will not otherwise appreciate the implications of a particular value. In short, existing fine particle level sensor technology is not a viable option for persons wishing to determine if an environment of interest has an elevated fine particle level.
In light of generally increasing poor air quality, coupled with a growing awareness of air quality issues, a need exists for simple solutions to indicate both actual air quality and the need for air quality solutions.